Johnson's natural philosophy and key to philosophical charts : illustrated with 500 cuts; being reduced photographic copies of all the diagrams contained in the author's philosophical series of indestructible school charts ; for the use of schools and families (1878)
ions of com-pressed or dilated air, which arrive at the exterior opening, transmittheir compressions or dilatations to portions of air smaller and smaller,and consequently transmit them with increased intensity. The form of the external ear of animals favors the collection of soundin the same… … The instrument is conical, terminated by a bell-shaped extremity, M,and provided with a suitable mouth-piece, L. .308 ACOUSTICS. As ill tlie case of the ear-trumpet, it was formerly supposed the ad-Aautage of the speaking-trumpet was due to the reflection of the undu-lations, in such a manner that…
Physics · Astronomy
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